Identification_Information: Citation: Citation_Information: Originator: Ralph R. Shroba Originator: Robert B. Scott Publication_Date: 2001 Title: Geologic Map of the Silt Quadrangle, Garfield County, Colorado Edition: 1.0 Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: Miscellaneous Field Studies Issue_Identification: MF-2331 Publication_Information: Publication_Place: Denver, Colorado Publisher: U.S. Geological Survey Online_Linkage: http://greenwood.cr.usgs.gov/pub/mf-maps/mf-2331/ Description: Abstract: New 1:24,000-scale geologic mapping in the Silt 7.5' quadrangle, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of the stratigraphy, structure, and geologic hazards in the area of the southwest flank of the White River uplift, the Grand Hogback, and the eastern Piceance Basin. The Wasatch Formation was subdivided into three formal members, the Shire, Molina, and Atwell Gulch Members. Also a sandstone unit within the Shire Member was broken out. The Mesaverde Group consists of the upper Williams Fork Formation and the lower Iles Formation. Members for the Iles Formation consist of the Rollins Sandstone, the Cozzette Sandstone, and the Corcoran Sandstone Members. The Cozzette and Corcoran Sandstone Members were mapped as a combined unit. Only the upper part of the Upper Member of the Mancos Shale is exposed in the quadrangle. From the southwestern corner of the map area toward the northwest, the unfaulted early Eocene to Paleocene Wasatch Formation and underlying Mesaverde Group gradually increase in dip to form the Grand Hogback monocline that reaches 45-75 degree dips to the southwest (section A-A'). The shallow west-northwest-trending Rifle syncline separates the northern part of the quadrangle from the southern part along the Colorado River. Geologic hazards in the map area include erosion, expansive soils, and flooding. Erosion includes mass wasting, gullying, and piping. Mass wasting involves any rock or surficial material that moves downslope under the influence of gravity, such as landslides, debris flows, or rock falls, and is generally more prevalent on steeper slopes. Locally, where the Grand Hogback is dipping greater than 60 degrees and the Wasatch Formation has been eroded, leaving sandstone slabs of the Mesa Verde Group unsupported over vertical distances as great as 500 m, the upper part of the unit has collapsed in landslides, probably by a process of beam-buckle failure. In the source area of these landslides strata are overturned and dip shallowly to the northeast. Landslide deposits now armor Pleistocene pediment surfaces and extend at least 1 km into Cactus Valley. Gullying and piping generally occur on more gentle slopes. Expansive soils and expansive bedrock are those unconsolidated materials or rocks that swell when wet and shrink when dry. Most floods are restricted to low-lying areas. Several gas-producing wells extract methane from coals from the upper part of the Iles Formation. Purpose: To update and reinterpret earlier geologic mapping, and to provide sufficient geologic information for land-use decisions. Supplemental_Information: Map political location: Garfield County, Colorado Compilation scale: 1:24,000 Geology mapped in 1992 to 1996. Compilation completed March 1997. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2001 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: Irregular. Mapping is continuing in the region, and a more complete map of this area may eventually be produced. Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -107.75 East_Bounding_Coordinate: -107.625 North_Bounding_Coordinate: 39.625 South_Bounding_Coordinate: 39.50 Keywords: Theme: Theme_Keyword_Thesaurus: American Geological Institute (AGI) Glossary of Geology Theme_Keyword: Geologic map Theme_Keyword: Cretaceous to Tertiary sedimentary rocks Theme_Keyword: Quaternary to Tertiary surficial deposits Theme_Keyword: Laramide compressional deformation Theme_Keyword: Geologic hazards Place: Place_Keyword_Thesaurus: U.S. Board on Geographic Names (BGN) Geographic Names Information System (GNIS) Place_Keyword: USA Place_Keyword: Colorado Place_Keyword: Garfield County Place_Keyword: Silt Stratum: Stratum_Keyword_Thesaurus: North American Stratigraphic Code Stratum_Keyword: Wasatch Formation Stratum_Keyword: Mesaverde Group Stratum_Keyword: Williams Fork Formation Stratum_Keyword: Iles Formation Stratum_Keyword: Mancos Shale Access_Constraints: none Use_Constraints: none. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Ralph R. Shroba Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: MS 913, Box 25046 DFC City: Denver State_or_Province: CO Postal_Code: 80225-0046 Contact_Voice_Telephone: 303-236-1292 Contact_Electronic_Mail_Address: rshroba@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: Browse_Graphic_File_Description: graphic representation of map layout Browse_Graphic_File_Type: PDF Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Data were entered and checked by the geologist that made the field observations. The attributes of this geospatial data set consist of text identifiers and numeric codes that indicate the identity of the geologic unit or type of geologic feature, and determine how each feature is colored or symbolized. To check attribute accuracy, a color check plot was visually compared to the geologist's original compilation. Discrepancies between the digital geospatial dataset and the original analog compilation were corrected as needed. Machine-created listings of unique attribute values were used to identify spelling errors or other inconsistencies, and corrections were made as needed. This map has been thoroughly reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Logical_Consistency_Report: Map elements were visually checked for overshoots, undershoots, duplicate features, polygon closure, and other errors by the author and by the GIS technician(s) that created the digital database. Automated (ArcInfo) routines were also used to check the databases for polygon label errors, line or point attribution errors, sliver polygons, dangling arcs, intersection errors, and projection information. Check plots of the map were reviewed by at least two other geologists for consistency with basic geologic principles and general conformity to USGS mapping standards. Completeness_Report: Data are complete: no features that could be accurately represented at the compilation scale of 1:24,000 were eliminated or generalized. The smallest area represented is approximately 102 square meters. All geospatial database elements are attributed. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Lines were primarily positioned by photointerpretation of aerial photographs by using a PG-2 photogrammetric plotter that rectified the position and transferred it to a basemap. Lines were digitized from the basemap by using a digitizer tablet having a resolution of 0.001 inch. Additional lines and point observations were added in the field by means of positions determined by a PLGR-95 GPS unit having accuracy of about 10 meters. Most positions on the map are estimated to be accurate closer than 30 m horizontally. Lineage: Process_Step: Process_Description: Polygons, lines, and points representing geologic features and data points were digitized from scale-stable compilation materials using the GSMCAD public domain program (USGS Open-File Report 96-007). Process_Date: 1999 Process_Step: Process_Description: The map data were exported to ARC/INFO by the GSMCAD export function to create ARC generate ASCII files. The ASCII files were then imported into ArcInfo by the GENERATE routine, and polygon topology built. Process_Date: 1999 Process_Step: Process_Description: The gsmdraw.aml program was used in ARC to produce a graphics file of the colored map. In addition an explanation sheet was produced that includes a correlation of map units diagram, a list of map unit names and corresponding symbols, and an explanation of graphical map symbols. Process_Date: 1999 Process_Step: Process_Description: Text map unit descriptors were added to the .AAT and .PAT database files for each coverage. Process_Date: 1999 Process_Step: Process_Description: Draft check plots of the geologic map and explanation were created and submitted for peer review. Geologists reviewed the plots for scientific validity and clarity and for conformity with USGS standards for stratigraphic nomenclature. Revisions were made to the geospatial database as needed. Process_Date: 1999 Process_Step: Process_Description: The database files, metadata, and check plots were edited by the USGS Central Publications Group, and revisions made to the geospatial database as needed. Process_Date: 2000 Process_Step: Process_Description: The geospatial database files and metadata were quality checked for completeness and consistency. Process_Date: 2001 Process_Step: Process_Description: Final preparation of the geospatial database for distribution, and preparation of map-on-demand files and metadata. Process_Date: 2001 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Polyconic Polyconic: Longitude_of_Central_Meridian: -107.68750000 Latitude_of_Projection_Origin: 39.50000 False_Easting: 0.0 False_Northing: 0.0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 10 Ordinate_Resolution: 10 Planar_Distance_Units: METERS Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1927 Ellipsoid_Name: Clarke 1866 Semi-major_Axis: 6378206.4 Denominator_of_Flattening_Ratio: 294.98 Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: The data are supplied in ARC/INFO export format. DATABASE STRUCTURE - ARC/INFO ==================================== The database of the map consists of three coverages (root name = silt), including corresponding info files: This GIS database includes related look-up tables, which store detailed attribute information. Arc/Info relates for each coverage are saved in a file named .rel. Use the RELATE command with the restore argument at the arc prompt to make the relates active. Alternatively, in Arctools, use the Relate environment: open dialog in the Manage - Relates flyout menu under the Arctools menu to make the relates active. siltpoly coverage: contains all contact lines and labelpoints for each geologic polygon; also contains lines that are limit of overturned strata. In the denvpoly.pat INFO file the LABEL item indicates the rock unit label (abbreviation) used to label the unit on the map. The DESC item contains the formal or informal unit name. The SOURCE item contains the numeric code used to identify the data source for the rock unit. The SYMBOL item contains the shadeset symbol number used by ArcInfo to plot a filled/shaded polygon. The symbol numbers in this coverage refer to the color524.shd shadeset. In the coverage's siltpoly.aat INFO file the NAME item contains the name given to the structural feature. The SOURCE item contains the numeric code used to identify the data source for the structural feature. The SYMBOL item contains the lineset symbol number used by ArcInfo to plot a line. The symbol numbers in this coverage refer to the geol_sfo.lin lineset. In the coverage's siltpoly.ref INFO file the SOURCE item lists the numeric code used to identify the data source. The scale item lists the scale of the source map. (This value is the denominator of the proportional fraction that identifies the scale of the map that was digitized or scanned to produce the digital map.) The AUTHORS item lists the author(s) or compiler(s) of source map entered as last name, first name or initial, and middle initial. The YEAR item lists the source (map) publication date. The REFERENCE item lists the remainder of the reference in USGS reference format. The INFO structure of these files is listed below: >SILTPOLY.AAT >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 FNODE# 4 5 B - > 5 TNODE# 4 5 B - > 9 LPOLY# 4 5 B - > 13 RPOLY# 4 5 B - > 17 LENGTH 8 18 F 5 > 25 SILTPOLY# 4 5 B - > 29 SILTPOLY-ID 4 5 B - > 33 LINECODE 3 3 I - > 36 NAME 30 30 C - > 66 SOURCE 4 4 I - > 70 SYMBOL 3 3 I - >SILTPOLY.PAT >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 AREA 8 18 F 5 > 9 PERIMETER 8 18 F 5 > 17 SILTPOLY# 4 5 B - > 21 SILTPOLY-ID 4 5 B - > 25 SOURCE 4 4 I - > 29 LABEL 10 10 C - > 39 DESC 100 100 C - > 139 SYMBOL 3 3 I - >SILTPOLY.CON >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 LINECODE 3 3 I - > 4 SYMBOL 3 3 I - > 7 TYPE 10 10 C - > 17 MODIFIER 20 20 C - > 37 CERTAINTY 15 15 C - > 52 DESC 100 100 C - >SILTPOLY.REF >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 SOURCE 4 4 I - > 5 SCALE 8 8 I - > 13 AUTHORS 200 200 C - > 213 YEAR 4 4 I - > 217 REFERENCE 250 250 C - siltline coverage: contains cross-section lines and a synclinal fold axis line. In the siltline.aat INFO file the NAME item indicates the name given to the structural feature. The SOURCE item contains the numeric code used to identify the data source for the structural feature. The DESC item contains the written description or explanation of the contact, boundary, or structural feature. The SYMBOL item contains the lineset symbol number used by ArcInfo to plot a line. The symbol numbers in this coverage refer to the geol_sfo.lin lineset. In the coverage's siltline.ref INFO file the SOURCE item lists the numeric code used to identify the data source. The scale item lists the scale of the source map. (This value is the denominator of the proportional fraction that identifies the scale of the map that was digitized or scanned to produce the digital map.) The AUTHORS item lists the author(s) or compiler(s) of source map entered as last name, first name or initial, and middle initial. The YEAR item lists the source (map) publication date. The REFERENCE item lists the remainder of the reference in USGS reference format. The INFO structure of these files is listed below: >SILTLINE.AAT >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 FNODE# 4 5 B - > 5 TNODE# 4 5 B - > 9 LPOLY# 4 5 B - > 13 RPOLY# 4 5 B - > 17 LENGTH 8 18 F 5 > 25 SILTLINE# 4 5 B - > 29 SILTLINE-ID 4 5 B - > 33 LINECODE 3 3 I - > 36 NAME 30 30 C - > 66 SOURCE 4 4 I - > 70 DESC 100 100 C - > 170 SYMBOL 3 3 I - >SILTLINE.CON >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 LINECODE 3 3 I - > 4 SYMBOL 3 3 I - > 7 TYPE 10 10 C - > 17 MODIFIER 20 20 C - > 37 CERTAINTY 15 15 C - > 52 DESC 100 100 C - >SILTLINE.STR >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 LINECODE 3 3 I - > 4 SYMBOL 3 3 I - > 7 TYPE 10 10 C - > 17 HORIZONTAL 20 20 C - > 37 VERTICAL 20 20 C - > 57 FOLD 15 15 C - > 72 PLUNGE 15 15 C - > 87 ACCURACY 15 15 C - > 102 CERTAINTY 15 15 C - > 117 DESC 100 100 C - >SILTLINE.REF >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 SOURCE 4 4 I - > 5 SCALE 8 8 I - > 13 AUTHORS 200 200 C - > 213 YEAR 4 4 I - > 217 REFERENCE 250 250 C - siltpnt coverage: Contains points recording site-specific observations and measurements, such as strike and dip of bedding. In the siltpnt.pat INFO file the PTTYPE item lists the type of point symbol, e.g., strike and of inclined bedding. The MARKER item lists the markerset used for a particular PTTYPE. MARKER value 1 = GEOSCAMP2.MRK, 2 = OILGAS.MRK, 3 = USGS.MRK. OILGAS.MRK and USGS.MRK are standard ArcInfo markersets. The SYMBOLCD item lists the marker symbol used by ArcInfo to identify the type of structural map symbol. Symbol numbers refer to symbols in the 3 markersets listed above. The STRIKE item contains the strike of bedding. Strike is an azimuthal angle (measured in degrees from 0 to 360 in a clockwise direction from North). The DIP item contains the dip of bedding. This value is an angle measured (in degrees 0 to 90) down from the horizontal; thus a horizontal dip is 0 degrees and a vertical dip is 90 degrees. The CALCANG item contains an interim value used to calculate SYM$ANGLE. The SYM$ANGLE item is the angle used to mathematically rotate the map point symbol to its proper orientation on the map. This item was set equal to the pseudoitem '$ANGLE' (calc SYM$ANGLE = $ANGLE). The SOURCE item lists the numeric code used to identify the data source. In the coverage's siltpnt.ref INFO file the SOURCE item lists the numeric code used to identify the data source. The scale item lists the scale of the source map. (This value is the denominator of the proportional fraction that identifies the scale of the map that was digitized or scanned to produce the digital map.) The AUTHORS item lists the author(s) or compiler(s) of source map entered as last name, first name or initial, and middle initial. The YEAR item lists the source (map) publication date. The REFERENCE item lists the remainder of the reference in USGS reference format. The INFO structure of these files is listed below: >SILTPNT.PAT >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 AREA 8 18 F 5 > 9 PERIMETER 8 18 F 5 > 17 SILTPNT# 4 5 B - > 21 SILTPNT-ID 4 5 B - > 25 PTTYPE 80 80 C - > 105 SYMBOLCD 3 3 I - > 108 STRIKE 3 3 I - > 111 DIP 3 3 I - > 114 CALCANG 4 4 I - > 118 SYM$ANGLE 4 4 I - > 122 MARKER 3 3 I - > 125 SOURCE 4 4 I - >SILTPNT.REF >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 SOURCE 4 4 I - > 5 SCALE 8 8 I - > 13 AUTHORS 200 200 C - > 213 YEAR 4 4 I - > 217 REFERENCE 250 250 C - Auxiliary files: color524.shd: This shadeset file defines the rgb values of colors assigned to polygons in the siltpoly coverage (see SYMBOL item). geol_sfo.lin: This lineset file defines geologic line types in the geologically themed coverages. geoscamp2.mrk: This markerset file defines the geologic markers in the geologically themed coverages. mf-2331_screen.pdf: A screen optimized file for viewing and printing a graphics version of the map and accessory elements using Adobe Acrobat viewing software (version 4.0). (Adobe Acrobat 4.0 viewing software is free and can be downloaded at the following URL: http://www.adobe.com/prodindex/acrobat/readstep.html) Accessory map elements displayed in this graphics file are: (1) geologic cross section A-A", (2) geologic cross section B-B', (3) correlation of map units diagram, (4) list of map unit symbols and names, and (5) explanation of map symbols. mf-2331_print.pdf: A print optimized file for viewing and printing a graphics version of the map and accessory elements using Adobe Acrobat viewing software (version 4.0). (Adobe Acrobat 4.0 viewing software is free and can be downloaded at the following URL: http://www.adobe.com/prodindex/acrobat/readstep.html) Accessory map elements displayed in this graphics file are: (1) geologic cross section A-A", (2) geologic cross section B-B', (3) correlation of map units diagram, (4) list of map unit symbols and names, and (5) explanation of map symbols. mf-2331_pamphlet.pdf: A detailed textual description of geologic map units and a brief discussion of deposits, structure, and geologic history of the map area. Can be displayed using the Adobe Acrobat viewing software (version 4.0). Entity_and_Attribute_Detail_Citation: >Database root name: silt >Label Desc >af Artificial fill (latest Holocene) >Qfp Flood-plain and stream-channel deposits (Holocene and late Pleistocene) >Qty Younger terrace alluvium (late Pleistocene) >Qtm Intermediate terrace alluvium (late Pleistocene) >Qto Older terrace alluvium (late middle Pleistocene) >Qba Basaltic alluvium (late middle Pleistocene) >Qg Gravelly alluvium (late and middle Pleistocene) >Qtt Oldest terrace alluvium (middle Pleistocene) >Qfy Younger fan-alluvium and debris-flow deposits (Holocene and latest > Pleistocene) >Qac Alluvium and colluvium, undivided (Holocene and late Pleistocene) >Qp Pediment deposits (middle Pleistocene) >Qc Colluvium, undivided (Holocene to middle? Pleistocene) >Qsw Sheetwash deposits (Holocene and late Pleistocene) >Qsw/Qlo Sheetwash deposits over loess >Qls Landslide deposits (Holocene to middle? Pleistocene) >Qd Debris-flow deposits (Holocene? to middle? Pleistocene >Qdo Older debris-flow deposits (early? Pleistocene) >Qlo Loess (late and middle? Pleistocene) >Qlo/Qty Loess over younger terrace alluvium >Qlo/Qtm Loess over intermediate terrace alluvium >Qlo/Qto Loess over older terrace alluvium >Qlo/Qd Loess over debris-flow deposits >Qlo/Qtt Loess over oldest terrace alluvium >Qlo/Qp Loess over pediment deposits >Qlo/Qtt/Qp Loess over oldest terrace alluvium over pediment deposits >Tw Wasatch Formation (in cross section only) (Eocene to Paleocene) >Tws Shire Member of Wasatch Formation (Eocene) >Twss Sandstone unit of Shire Member of Wasatch Formation >Twm Molina Member of Wasatch Formation (Eocene) >Twa Atwell Gulch Member of Wasatch Formation (in cross section only) > (Paleocene) >Twav Volcaniclastic-rich unit of Atwell Gulch Member of Wasatch Formation >Twal Lower unit of Atwell Gulch Member of Wasatch Formation >Kmv Mesaverde Group (in cross section only) (Upper Cretaceous) >Kwf Williams Fork Formation of Mesaverde Group >Kwfu Upper unnamed sandstone unit of Williams Fork Formation of Mesaverde Group >Kwfl Lower unnamed sandstone unit of Williams Fork Formation of Mesaverde Group >Ki Iles Formation of Mesaverde Group >Kir Rollins Sandstone Member of Iles Formation of Mesaverde Group >Kicc Cozzette Sandstone and Corcoran Sandstone Members, undivided, of the Iles > Formation of Mesaverde Group >Kmvb Baked zone in the Mesaverde Group >Kmu Mancos Shale, Upper member (Upper Cretaceous) >DEFINITION OF LINECODES IN THE COVERAGES (LINECODES AND DESC IN THE .CON AND .STR >FEATURES IN THE DATABASE------------------------- >LINECODE | DESC > 1 | contact; certain > 2 | contact; approximately located > 41 | water boundary > 81 | map boundary (lines of latitude or longitude) > 88 | limit of overturned strata > 98 | cross-section line > 413 | fold axis; syncline; certain Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: Central Publications Group Address: MS 902, Box 25046, DFC City: Denver State_or_Province: CO Postal_Code: 80225-0046 Contact_Voice_Telephone: 303-236-5486 Contact_Electronic_Mail_Address: webmaster@greenwood.cr.usgs.gov Distribution_Liability: Although this digital spatial data has been subjected to rigorous review and is substantially complete, it is released on the condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ARCE, SHP Format_Version_Number: ArcInfo version 8.0.2 File_Decompression_Technique: .tar.gz - UNIX gzip-compressed TAR file - use GNU zip and TAR .ZIP - DOS/Windows ZIP archive - use WinZip, PKZip, or similar to extract Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: Fees: none Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S.Geological Survey Contact_Address: Address_Type: mailing address Address: USGS Information Services Address: Box 25286 City: Denver State_or_Province: CO Postal_Code: 80225 Country: United States Contact_Voice_Telephone: 1-888-ASK-USGS Resource_Description: MF-2331 (Map-on-Demand) Distribution_Liability: none Standard_Order_Process: Non-digital_Form: Available as one printed sheet plus one pamphlet. Order from USGS at the address listed above or see http://rmmcweb.cr.usgs.gov/public/mod/order.html for more ordering information. Fees: for current prices please see http://rmmcweb.cr.usgs.gov/public/mod/order.html Metadata_Reference_Information: Metadata_Date: 20000619 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Ralph R. Shroba Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: U.S. Geological Survey Address: MS 913, Box 25046 DFC City: Lakewood State_or_Province: CO Postal_Code: 80225-0046 Contact_Voice_Telephone: 303-236-1292 Contact_Electronic_Mail_Address: rshroba@usgs.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998